[TUHS] A/UX [was Linux is on-topic]

[Andrew Warkentin]

On 7/20/20, Derrik Walker v2.0 <dwalker at doomd.net> wrote:
>
> Interestingly enough. MkLinux was actually ported to Old World PowerMacs by
> Apple and HP.  I think they also made.a version PCs too.
>

There was an early version of MkLinux for PCs but I'm not sure if
there was ever a complete distribution.

On 7/20/20, Larry McVoy <lm at mcvoy.com> wrote:
>
> This isn't quite the same but Victor Yodaiken wrote a real time kernel
> that ran all of Linux as a user process.  Super cool idea and it worked
> great, he would demo it sampling the parallel port while Linux was running
> some X11 perf thing, tarring up /usr and untarring on nfs://server/tmp/usr
> and doing a ftp transfer.  Basically beating the crap out of Linux as
> hard as he could while running a real time sampler and it never missed.
>
> Clem should pay attention, in my opinion, this is how you do Unix and
> real time.  Because Unix is time sharing and throughput, that is the
> opposite of what real time is.  Wedging real time into Unix is a mistake.
>

QNX manages to do realtime fairly decently while still being
Unix-like, although it's certainly not a conventional Unix. With a
multi-server OS with a properly designed microkernel, it is possible
for realtime threads to more or less ignore the fact that they're
running on a Unix-like OS (provided that they can access some kind of
IPC API that closely matches that of the kernel) since all the OS
services other than the microkernel are running beside them at
non-realtime priorities, and not underneath them as in a conventional
OS. It's kind of doing the same thing as running a Unix kernel as a
process under a realtime kernel, but the Unix environment is
implemented by servers and libraries instead of a monolithic kernel.